| From: | Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Use extended statistics to estimate (Var op Var) clauses |
| Date: | 2021-12-22 00:50:29 |
| Message-ID: | 68FB4185-A650-42C4-AE8F-94F28E358637@enterprisedb.com |
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| Thread: | |
| Lists: | pgsql-hackers |
> On Dec 21, 2021, at 4:28 PM, Mark Dilger <mark(dot)dilger(at)enterprisedb(dot)com> wrote:
>
> Maybe there is some reason this is ok.
... and there is. Sorry for the noise. The planner appears to be smart enough to know that column "salary" is not being changed, and therefore NEW.salary and OLD.salary are equal. If I test a different update statement that contains a new value for "salary", the added assertion is not triggered.
(I didn't quite realize what the clause's varnosyn field was telling me until after I hit "send".)
—
Mark Dilger
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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